Fix failing knewfilemenu test and underlying reason for its failure

Summary:
After ef57863a73c0e58b94f9f9f0aa1f4e918d98e79a, the knewfilemenu test started failing. This was for three reasons:

1. I forgot to run the tests, sorry about that!
2. The test itself had an error that was being masked by the bug fixed in that commit
3. KIO::mkdir is a subclass of SimpleJob, and is capable of creating directorties, so the previous code did not emit the correct signals because the SimpleJob condition can result in the job having its newDirectoryURL property set

This patch fixes the above issues by correcting the bug in the test and always checking for the newDirectoryURL property no matter what kind of job it is.

Test Plan:

• All tests now pass
• Copying files and folders still works

Reviewers: Frameworks, dfaure, elvisangelaccio, aacid

Reviewed By: dfaure

Subscribers: kde-frameworks-devel

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D17911

(cherry picked from commit 673ee2f1115c86cead2bda784ba52502c6305c96)